CA readers know that virtually all of the “independent” IPCC reconstructions purporting to compare modern and MWP temperatures use Graybill strip bark chronologies and/or Yamal. In various posts, problems with strip bark chronologies have been discussed, including discussion of Pete Holzmann’s observation based on our sampling at Almagre that strip bark trees seemed to show a growth pulse after the strip bark event. Indeed, this topic was under discussion in the very thread that the Climategate dossier was first mentioned (though no one noticed this until Gavin Schmidt brought it to our attention.)
In one of the last Climategate emails in October 2003 prior to MM2003, Malcolm Hughes (368. 1065785323.txt Oct 10, 2003) observed that he was “sitting on the bones of a manuscript” reporting the phenomenon of dramatic growth pulses after strip bark formation:
I am sitting on the bones of a manuscript in which I had someone spend
several months checking many hundreds of bristlecone and similar cross-sections and cores in our store. They found only a few dozen – less than 10%, where either pith was present, or the innermost ring could reasonably be described as ‘near pith’. If you have seen these stripbark montane 5-needle pines, and ever tried to core them, you will understand why. A further problem arises from the observation that radial increment may increase rather dramatically in the period after most of the bark dies back, but of course we don’t know when that was.
Now compare this to the CA post:
Note, as reader Erasmus de F observed, the tremendous growth pulse in the surviving part of the trunk immediately following the glacier scar.
If you drilled a core in the center of the surviving “strip” bark in the scarred spruce, you would get a huge growth pulse in the late 19th century; if you drilled a core at the edge of the surviving strip bark, you would get correlated but narrow widths. This is exactly the situation that we hypothesized at Almagre strip bark (our Tree 31 discussed here.) Here’s a ring width plot from the prior post. The glacier-scarred tree would yield a graphic like this:
Hughes observed that the date of the strip bark event was not knowable, but in some cases, dating seemed plausible. In the Miracle post, the event had been dated quite precisely to glacier expansion in the 1840s. It seemed highly plausible that strip barking in a number of Almagre bristlecones had also occurred in the very cold and snowy 1840s. Because the growth pulse was highly nonlinear – six sigma deviations in some cases – it wouldn’t take more than a few such trees in a typical sample to affect the chronology.
Seven years later, Hughes is still sitting on the “bones” of his manuscript describing the post-event growth pulse from strip bark trees.
